The present invention relates, in general, to an apparatus and method for making gas-filled filling bodies.
Nothing in the following discussion of the state of the art is to be construed as an admission of prior art.
Gas-filled-normally air-filled-filling bodies are increasingly used as filling material for transport of sensitive goods in particular. Compared to traditional filling materials for packaging purposes, like e.g. filling bodies of foamed plastic, gas-filled filling bodies can be produced, at the site where they are needed, from a half-tubular film mounted on a reel by “blowing up” the film so that the volume of the filling bodies increases by a multiple, typically at least by the factor 10 compared to the initial volume of the film reel. After use, air can easily be released again from the filling bodies so that the amount of waste is reduced, although recycling of the films is, of course, easily possible.
International publication no. WO 02/26589 A1 discloses a continuously operating filling apparatus for making such gas-filled filling bodies, wherein a pre-fabricated half-tubular film which is open on one side is moved past a gas filling device, deflected at an angle, and then welded under the action of a heated band of Teflon-coated steel via a welding runner. This apparatus is complex and requires substantial maintenance works as a result of the use of Teflon-coated steel.
German utility model no. DE 203 15 643 U discloses an apparatus for making gas-filled filling bodies, having a welding tool configured as welding runner which directly rests upon the film material. The half-tubular film is hereby transported by belts as well as guide wheels. The transport of film requires a fairly complex mechanism with several drive elements which must be precisely synchronized in order to prevent, at commencement of the filing operation, the half-tubular film, which still is made from upper and lower film portions loosely lying upon one another, from escaping the machine, or to prevent a crease formation between the upper and lower film portions, which would render an air-tight welding impossible. The respective drive devices with gear mechanisms are thus expensive, require relatively large installation space, and require a drive motor with relatively high power as a result of friction and gear losses.
It would therefore be desirable and advantageous to provide an improved apparatus and method for making gas-filled filling bodies to obviate prior art shortcomings.